VM handoff does not lose computing state, but it only loses network state because the IP address is changed. And this issue is a bit different from choosing lowest common denominator for the CPU mode. In short, we use lowest common denominator CPU model to ensure the VM can be migrated every different x86 machine that might different CPU flags (The detail explanation is explained in tech report section '5.1 Portability of the VM' http://reports-archive.adm.cs.cmu.edu/anon/2015/CMU-CS-15-123.pdf).